BLACK DIAMOND WATERMELON

Black Diamond heirloom melons are an old favorite and the quintessential watermelon; they perform excellently in southern climates. These watermelons are taken seriously in the town of Luling, Texas, at the annual “Watermelon Thump,” an annual festival to celebrate local watermelon industry, in which Black Diamond watermelons are a favorite. This variety of watermelon, grown by Texans Allen and Shane Watts, reached a record of 81 pounds and won the contest at the 2005 Watermelon Thump.

Sowing: In cool climates, Black Diamond watermelon seeds should be started indoors, but no sooner than a month before transplanting; plant three seeds per peat pot, 1/4″ deep. Provide heat to keep the soil at least 80-85 degrees F. Cut off all but the strongest seedling as soon as true leaves appear, and transplant about a week after frost; put two or three plants in each hill with a 6-8′ space in all directions. Gardeners in warm climates will be able to direct sow watermelons as soon as the soil temperature reaches at least 75 degrees F, planting six seeds per hill with 6-8′ of space in all directions. Thin to the strongest two or three plants as soon as the seedlings appear. Black Diamond watermelon seeds should be planted in full sun and rich, loose soil. Young seedlings may benefit from black plastic to warm up the soil.

Growing: As soon as the vines begin to develop, apply a thick layer of mulch to control weeds and protect the melons from soil contact. Keep the soil moist until the fruit begins to grow, then water only if the soil dries out completely. Watch out for insect pests, which can be a problem.

Harvesting: Gardeners use many different methods of testing whether their watermelons are ripe, but knowing the approximate mature size of the melon helps to determine when it is nearing ripeness. One test is to knock on the watermelon with your knuckles, listening for a dull thump rather than a hollow ring. Another method is to check the underside of the melon where it rests on the ground; the skin should be a rich yellow. Also, the curling tendril closest to the stem of the melon often indicates ripeness when it begins to turn brown. Watermelons usually keep for several weeks in a cool place.

Seed Saving: Watermelons will cross with other varieties of watermelon, so isolation may be necessary to ensure genetic purity. When the melon is ripe, the seeds will be mature. Cut open the melon and remove the seeds; wash them to remove the sticky residue. Spread them out to dry for a week, then store them in a cool place for up to four years.

Latin Name: Citrullus lanatus

Type: Open Pollinated, Warm Season

USDA Zones: 3, 4, 5, 6, 7, 8, 9, 10, 11, 12

Seeds per Ounce: 200

Planting Method: Direct Sow

Sunlight: Full Sun

Height: 16 Inches

Color: Red